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U.S. Department of Energy
Office of Scientific and Technical Information

Subsidence and stability studies for underground coal gasification

Technical Report ·
OSTI ID:5222779
By removing from the calculation in later iterations roof elements in a tensile state of stress (which are assumed to fall), we have improved the nonlinear finite-element techniques previously used for predicting subsidence at the Hoe Creek underground coal gasification site. To supplement the finite element approach, we have applied some elasticity solutions to the problem in a nondimensional parametric formulation. The elastic solutions indicate the extent of the induced tensile zone in the roof, and we have used this zone to predict the arch height in an underground cavity. The arch heights found by this method compare favorably with those found by the finite element method with extraction of roof elements. Finally, we have conducted a series of laboratory core tests to determine material properties of Hoe Creek rock samples to provide better data, both for future subsidence studies and for comparison of predicted subsidence with field measurements during and after coal gasification experiments.
Research Organization:
California Univ., Livermore (USA). Lawrence Livermore Lab.
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
5222779
Report Number(s):
UCID-17674
Country of Publication:
United States
Language:
English